Liquid hydrogen temperature zone valve bidirectional sealing test system and test method

Abstract

The present application relates to the technical field of valve performance testing, and in particular to a bidirectional sealing test system and test method for liquid hydrogen temperature zone valves. The test system includes a liquid nitrogen cryogenic tank and a liquid helium cooling chamber; the liquid nitrogen cryogenic tank is connected to a liquid nitrogen storage device; the liquid helium cooling chamber is located in the liquid nitrogen cryogenic tank and is connected to the liquid helium storage device; the air inlet branch is connected to the air inlet of the valve to be tested, and the air outlet branch is connected to the air outlet of the valve to be tested; when the switching device is in the forward state, the first air duct is connected to the air outlet branch, and the second air duct is connected to the air inlet branch; when the switching device is in the reverse state, the first air duct is connected to the air inlet branch, and the second air duct is connected to the air outlet branch. The present application realizes the function of performing forward and reverse sealing tests on valves with bidirectional sealing structures such as liquid hydrogen check valves, which not only optimizes the test process and improves test efficiency, but also helps to reduce potential leakage and blockage problems caused by pipeline switching.

Description

Technical Field

[0001] The present application relates to the technical field of valve performance testing, and in particular to a liquid hydrogen temperature zone valve bidirectional sealing test system and test method. Background Art

[0002] Low-temperature liquid hydrogen storage and transportation has the advantages of high storage traffic density and low long-distance transportation cost, and is an ideal hydrogen energy storage and transportation mode. Liquid hydrogen storage tanks, liquid hydrogen tank trucks, liquid hydrogen cylinders, liquid hydrogen pipelines, etc. are all common liquid hydrogen storage and transportation equipment. Among them, various forms of valves such as stop valves, check valves, and emergency shut-off valves are important components of liquid hydrogen storage and transportation equipment, and play a key role in the medium sealing and start-stop efficiency of liquid hydrogen containers and pipelines. During their service, the above-mentioned valves are in contact with liquid hydrogen or low-temperature hydrogen most of the time, and the working environment is extremely harsh. The most common failure mode is leakage caused by excessive deformation of the metal seals at the valve fitting at extremely low temperatures. Once liquid hydrogen leaks, it will gasify in a very short time to generate a large amount of hydrogen, which is prone to combustion or even explosion. Therefore, the low-temperature sealing performance of liquid hydrogen valves is its key performance, and it is necessary to test and verify the sealing performance of liquid hydrogen valves in a real medium environment.

[0003] In an existing multi-state liquid hydrogen valve test device, the front end of the helium booster pipeline is connected to the high-pressure helium cylinder and the helium switch valve in sequence, and the rear end is divided into three branches. The first branch is connected to the first helium pressure reducing valve, the first helium stop valve, the first pressure sensor and the mixer in sequence to achieve pressure regulation of the rear section of the test valve. The second branch is connected to the second helium stop valve and the inlet stop valve in sequence to achieve functions such as replacement of the test valve. The third branch is connected to the third helium pressure reducing valve, the third helium stop valve, the third pressure sensor and the liquid hydrogen storage tank in sequence to achieve pressure regulation inside the liquid hydrogen storage tank. By regulating the temperature and pressure parameters of the liquid hydrogen medium before and after the test valve, in addition to the conventional saturated state, it can also achieve tests of various complex working conditions such as supercritical hydrogen, supercooled hydrogen, and transcritical hydrogen; by regulating the flow rate of liquid hydrogen before and after the test valve, it can achieve tests of two working conditions: stable flow and fluctuating flow; at the same time, through the helium mass spectrometer, flowmeter and other devices, it can effectively achieve test contents such as internal leakage and external leakage of the valve.

[0004] When using this device to perform a bidirectional sealing test on a valve, the valve needs to be changed in direction and reinstalled in an insulating box to connect to the pipeline. This process will inevitably affect the simulated working conditions, and the environment in which the valve is located needs to be readjusted, which not only affects the test efficiency, but also the test results. Summary of the invention

[0005] In order to solve the above problems, the present application provides a liquid hydrogen temperature zone valve bidirectional sealing test system and test method.

[0006] The present application provides a liquid hydrogen temperature zone valve bidirectional sealing test system and test method using the following technical solutions: In a first aspect, a liquid hydrogen temperature zone valve bidirectional sealing test system comprises: A cryogenic container, comprising a liquid nitrogen cryogenic tank and a liquid helium cooling chamber; the liquid nitrogen cryogenic tank is selectively connected to a liquid nitrogen storage device through a liquid guide tube; the liquid helium cooling chamber has a closed chamber, is located in the liquid nitrogen cryogenic tank, is selectively connected to the liquid helium storage device through a liquid inlet pipe, and is used to accommodate a valve body of a valve to be tested, and a first interface and a second interface are provided on the valve to be tested; An air inlet branch, connected to an air inlet of a valve to be tested, to introduce helium into the valve to be tested; The air outlet branch is used to communicate with the air outlet of the valve to be tested and is used to determine the sealing condition of the valve to be tested; A first gas guide pipe, one end of which passes through the liquid helium cooling chamber and is connected to a first interface of the valve to be tested; A second gas guide pipe, one end of which passes through the liquid helium cooling chamber and is connected to the second interface of the valve to be tested; the other end of the first gas guide pipe and the other end of the second gas guide pipe are connected to the inlet branch and the outlet branch through a switching device, and the switching device has a forward state and a reverse state; When the switching device is in a forward state, the first air duct is connected to the outlet branch, and the second air duct is connected to the inlet branch; when the switching device is in a reverse state, the first air duct is connected to the inlet branch, and the second air duct is connected to the outlet branch.

[0007] Through the above technical solution, the switching device is used to realize the connection direction of the inlet branch, the outlet branch and the valve to be tested, and the direction of the helium flow through the valve to be tested is controlled, so as to realize the function of forward and reverse sealing test of valves with bidirectional sealing structure such as liquid hydrogen check valve, ensure the accurate evaluation of the sealing performance of the valve under different working conditions, improve the flexibility and efficiency of the test, and avoid the risk of reduced test efficiency and air being brought into the pressure test pipeline due to the replacement of the inlet and outlet pipelines of the experimental module. At the same time, it not only optimizes the test process and improves the test efficiency, but also helps to reduce potential leakage and blockage problems caused by pipeline switching, especially under low temperature conditions of -253℃, the risk of air condensation blocking the test pipeline is effectively avoided.

[0008] At the same time, the liquid helium cooling chamber is located in the liquid nitrogen cryogenic tank. The liquid nitrogen in the liquid nitrogen cryogenic tank can initially cool down the valve to be tested in the liquid helium cooling chamber, and the liquid helium in the liquid helium cooling chamber can further cool down the valve to be tested. Compared with directly using liquid helium for cooling, this solution can reduce the consumption of liquid helium and reduce the test cost. The liquid helium cooling chamber is set in the liquid nitrogen cryogenic tank. On the one hand, it provides a dual cold preservation effect for the valve to be tested. On the other hand, during the test, the liquid helium cooling chamber is placed in the low-temperature liquid nitrogen tank for cooling and cold preservation, which can reduce the thermal influence of the inner wall temperature of the liquid helium cooling chamber on the liquid helium, further realize more efficient use of liquid helium, further reduce the consumption of liquid helium, and reduce the test cost.

[0009] Optionally, the switching device includes: a first switching pipeline, one end of which is connected to the air inlet branch and the other end of which is connected to the air outlet branch; two stop valves are provided on the first switching pipeline; the first air guide pipeline is connected to the middle of the first switching pipeline and is located between the two stop valves; The second switching pipeline has one end connected to the air inlet branch and the other end connected to the air outlet branch. Two stop valves are provided on the second switching pipeline. The second air guide pipeline is connected to the middle part of the second switching pipeline and is located between the two stop valves.

[0010] Through the above technical solution, the first gas duct and the second gas duct can be connected to the air inlet branch and the air outlet branch between the two stop valves, ensuring that the gas can flow along the predetermined path in different test stages. By controlling the opening and closing of the stop valves, the various pipelines can be effectively isolated or connected, achieving precise control of the gas flow direction, thereby flexibly switching between forward and reverse sealing tests.

[0011] Optionally, a heating branch is further included, wherein the heating branch includes a heater and a second booster pump connected in sequence through pipelines, and one end of the heating branch can be selectively connected to the first helium storage device, and the other end is connected to the first gas guide pipeline.

[0012] Through the above technical solution, the selective connectivity of the heating branch can be flexibly connected to the first helium storage device and the first gas guide pipe to heat and recover the helium in the loop.

[0013] Optionally, two pressure sensors are provided on the air intake branch, wherein one of the pressure sensors is located between the first helium storage device and the heating branch, and the other pressure sensor is used to measure the pressure of the second air duct.

[0014] Through the above technical solution, the pressure changes of the gas before and after pressurization can be monitored in real time, which is helpful to ensure the stability of the gas pressure and predict potential pressure problems.

[0015] Optionally, it also includes a heat-conducting coil, and the valve to be tested is provided with a valve connecting pipe; The heat conducting coil is located in the liquid helium cooling chamber and is wound around the valve pipe. One end of the heat conducting coil passes through the liquid helium cooling chamber and is selectively connected to the liquid conducting pipe, and the other end passes through the liquid helium cooling chamber and is connected to the liquid nitrogen cryogenic tank.

[0016] Through the above technical solution, by directly introducing liquid nitrogen into the contact point of the valve pipe, the heat conduction effect is enhanced, thereby more effectively reducing the temperature of the valve to be tested to meet the strict requirements of valve testing in the liquid hydrogen temperature zone.

[0017] Optionally, also include: a first connecting pipe, one end of which is connected to the second air guide pipe and the other end of which is connected to the liquid guide pipe, and a stop valve is provided on the first connecting pipe; A second connecting pipeline has one end connected to the first gas guiding pipeline and the other end connected to the liquid nitrogen cryogenic tank. A stop valve is provided on the second connecting pipeline.

[0018] Through the above technical solution, liquid nitrogen directly flows into the valve to be tested to cool the valve to be tested, quickly reducing the temperature of the valve to be tested to -180°C, thereby improving the cooling efficiency and shortening the cooling time of the valve to be tested before the test.

[0019] Optionally, the wall of the liquid helium cooling chamber is a double-layer structure and is provided with an interface for communicating with a vacuum pumping device.

[0020] Through the above technical solution, the air and other gases in the double-layer structure are discharged using a vacuum device, which can reduce the heat conduction and convection of gas molecules, reduce the heat load of the liquid helium cooling chamber, improve the insulation effect, reduce the vaporization loss of liquid helium, and reduce the test cost.

[0021] Optionally, the tank wall of the liquid nitrogen low-temperature tank is a double-layer structure, and an insulating layer is provided between the inner and outer layers.

[0022] By adopting the above technical solution, the insulation effect is improved, the vaporization loss of liquid helium is reduced, and the test cost is reduced.

[0023] Optionally, it further includes a temperature measuring component, which includes a second temperature sensor. The second temperature sensor is used to be arranged on the valve to be tested to measure the temperature of the valve to be tested.

[0024] Through the above technical solutions, the test environment can be precisely controlled and monitored, the accuracy and reliability of the test can be improved, and the performance test results of the valve in the liquid hydrogen temperature range can be ensured to be true and valid.

[0025] Optionally, it further includes a first pressure sensor and a second pressure sensor, wherein the first pressure sensor and the second pressure sensor are arranged in the intake branch and located on both sides of the boost pump.

[0026] By adopting the above technical solution, the pressure change of gas before and after pressurization can be monitored in real time, which is conducive to ensuring the stability of gas pressure and predicting potential pressure problems. By comparing the pressure difference before and after pressurization, the working state of the booster pump can be adjusted to ensure that the gas pressure meets the test requirements.

[0027] In a second aspect, a liquid hydrogen temperature zone valve bidirectional sealing test method is provided, based on the above-mentioned liquid hydrogen temperature zone valve bidirectional sealing test system, comprising the following steps: The valve to be tested is installed in the liquid helium cooling chamber and connected with the air inlet branch and the air outlet branch; Introduce liquid nitrogen into the liquid nitrogen low temperature tank to cool down the valve to be tested; Introduce liquid helium into the liquid helium cooling chamber to further cool the valve to be tested; After cooling, the first air guide pipe is connected to the air outlet branch, the second air guide pipe is connected to the air inlet branch, the valve to be tested is closed, helium is introduced into the valve to be tested through the air inlet branch, and the positive sealing condition of the valve is determined through the air outlet branch; The first air guide pipe is connected to the air inlet branch, the second air guide pipe is connected to the air outlet branch, the valve to be tested is closed, helium is introduced into the valve to be tested through the air inlet branch, and the reverse sealing condition of the valve to be tested is determined through the air outlet branch.

[0028] In summary, the present application includes at least one of the following beneficial technical effects: 1. The switching device is used to realize the connection direction between the inlet branch, the outlet branch and the valve to be tested, and the direction of the helium flow through the valve to be tested is controlled, so as to realize the function of forward and reverse sealing test of valves with bidirectional sealing structure such as liquid hydrogen check valve, improve the flexibility and efficiency of the test, and avoid the risk of reduced test efficiency and air being brought into the pressure test pipeline due to replacement of the inlet and outlet pipelines of the experimental module. At the same time, it not only optimizes the test process and improves the test efficiency, but also helps to reduce potential leakage and blockage problems caused by pipeline switching.

[0029] 2. The liquid helium cooling chamber is located in the liquid nitrogen cryogenic tank. The liquid nitrogen in the liquid nitrogen cryogenic tank can initially cool down the valve to be tested in the liquid helium cooling chamber, and the liquid helium in the liquid helium cooling chamber can further cool down the valve to be tested. The liquid helium cooling chamber is located in the liquid nitrogen cryogenic tank. On the one hand, it provides a dual cooling effect for the valve to be tested. On the other hand, during the test, the liquid helium cooling chamber is placed in the low-temperature liquid nitrogen tank for cooling and cooling, which can reduce the thermal impact of the inner wall temperature of the liquid helium cooling chamber on the liquid helium, further realize more efficient use of liquid helium, further reduce the consumption of liquid helium, and reduce the test cost.

[0030] 3. One end of the heating branch can be selectively connected to the first helium storage device, and the other end can be connected to the first gas pipeline. It can be flexibly connected to the first helium storage device and the first gas pipeline to heat and recover the helium in the loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the bidirectional sealing test system of the liquid hydrogen temperature zone valve in this application; Figure 2 yes Figure 1 A partial connection diagram of the liquid nitrogen cryogenic tank, the liquid helium cooling chamber, the liquid nitrogen storage device and the liquid helium storage device; Figure 3 yes Figure 1 Schematic diagram of partial connection of liquid nitrogen cryogenic tank, liquid helium cooling chamber and heat transfer coil; Figure 4 and Figure 5 yes Figure 1 A schematic diagram of a partial connection between the middle air intake branch and the air outlet branch through the first switching pipeline and the second switching pipeline; Figure 6 and Figure 7 yes Figure 1 Schematic diagram of the partial connection between the middle air intake branch and the valve to be tested through the heating branch.

[0032] Description of reference numerals: 100, valve to be tested; 101, first interface; 102, second interface; 1, liquid nitrogen cryogenic tank; 110, liquid guide tube; 2, liquid helium cooling chamber; 210, liquid inlet pipe; 3, liquid nitrogen storage device; 4, liquid helium storage device; 41, second helium storage device; 42, liquid helium tank; 5, air inlet branch; 51, air inlet pipe; 52, first helium storage device; 53, first booster pump; 6, air outlet branch; 61, air outlet pipe; 62, alcohol bubble counter; 63, exhaust pipe; 64, flow meter; 7, actuator; 8, first discharge pipe; 9, second discharge pipe; 10, heat transfer coil; 11, first connecting pipe; 12, second connecting pipe; 13, first air guide pipe ; 14. second gas duct; 15. first switching duct; 16. second switching duct; 17. heating branch; 171. heater; 172. second booster pump; V1. helium pressure regulating valve; V2. upstream isolation valve; V3. purge valve; V4. downstream isolation valve; V5. discharge valve; V6. safety valve; V7. liquid helium regulating valve; V8. helium regulating valve; V9. liquid nitrogen inlet valve; TC1. first temperature sensor; TC2. second temperature sensor; TC3. third temperature sensor; TC4. fourth temperature sensor; TC5. fifth temperature sensor; TC6. sixth temperature sensor; TC7. seventh temperature sensor; TC8. eighth temperature sensor. DETAILED DESCRIPTION

[0033] The following will be combined with the attached Figure 1-7 , the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The embodiment of the present application discloses a bidirectional sealing test system for liquid hydrogen temperature zone valves, which is used to perform bidirectional sealing tests on the liquid hydrogen temperature zone performance of valves. Applicable liquid hydrogen valve types include but are not limited to stop valves, regulating valves, check valves, emergency shut-off valves, ball valves, and butterfly valves; liquid hydrogen valve tests that can be performed include but are not limited to normal temperature sealing tests, low temperature and low pressure sealing tests, low temperature and high pressure opening and closing tests, low temperature and high pressure sealing tests, and low temperature fugitive emission tests.

[0036] Reference Figure 1 The liquid hydrogen temperature zone valve bidirectional sealing test system includes a low-temperature container, an air inlet branch 5, an air outlet branch 6, a heat conduction coil 10, a first air guide pipe 13, a second air guide pipe 14, a switching device, and a temperature measuring component.

[0037] Reference Figure 2 The cryogenic container includes a liquid nitrogen cryogenic tank 1 and a liquid helium cooling chamber 2. The liquid nitrogen cryogenic tank 1 is selectively connected to the liquid nitrogen storage device 3 through a liquid conduit 110. In this embodiment, the liquid nitrogen storage device 3 is a liquid nitrogen storage tank, and a liquid nitrogen inlet valve V9 is provided on the liquid conduit 110. When the liquid nitrogen inlet valve V9 is opened, the liquid nitrogen storage device 3 introduces liquid nitrogen into the liquid nitrogen cryogenic tank 1.

[0038] The liquid helium cooling chamber 2 has a closed chamber, and can be selectively connected to the liquid helium storage device 4 through the liquid inlet pipe 210. The liquid inlet pipe 210 is provided with a liquid helium regulating valve V7. When the liquid helium regulating valve V7 is opened, the liquid helium storage device 4 introduces liquid helium into the liquid helium cooling chamber 2. The liquid helium cooling chamber 2 is used to accommodate the valve 100 to be tested, and is located in the liquid nitrogen low temperature tank 1. In this embodiment, the valve 100 to be tested is provided with an air inlet 101, an air outlet 102 and a valve pipe.

[0039] Specifically, the liquid helium storage device 4 includes a second helium storage device 41 and a liquid helium tank 42. The second helium storage device 41 is connected to the top of the liquid helium tank 42. A helium regulating valve V8 is connected between the second helium storage device 41 and the liquid helium tank 42. One end of the liquid inlet pipe 210 extends into the bottom of the liquid helium tank 42, and the other end is connected to the top of the liquid helium cooling chamber 2. The liquid helium tank 42 is a mobile liquid helium tank, and the second helium storage device 41 is a helium cylinder. The pressure of the liquid helium tank 42 is lower than the pressure of the helium cylinder. The pressure difference is conducive to the transportation of liquid helium from the liquid helium tank 42 to the liquid helium cooling chamber 2. A pressure sensor is provided on the second helium cylinder to measure the outlet pressure of the second helium cylinder.

[0040] The valve body of the valve to be tested 100 is located in the liquid helium cooling chamber 2. In this embodiment, the valve to be tested 100 is a control valve. Figure 1 , the actuator 7 of the control valve is located outside the liquid helium cooling chamber 2 ( Figures 2 to 7 , the actuator 7 of the control valve is not shown). The liquid helium cooling chamber 2 is located in the liquid nitrogen cryogenic tank 1, and the liquid nitrogen in the liquid nitrogen cryogenic tank 1 can initially cool the valve 100 to be tested in the liquid helium cooling chamber 2. The liquid helium in the liquid helium cooling chamber 2 can further cool the valve 100 to be tested. Compared with directly using liquid helium for cooling, this solution can reduce the consumption of liquid helium and reduce the test cost.

[0041] In this embodiment, the wall of the liquid helium cooling chamber 2 is a double-layer structure, and is provided with an interface C4 for communicating with a vacuum pumping device. Specifically, a liquid helium inlet vacuum insulation pipeline is provided on the liquid helium cooling chamber 2, and an interface C4 is provided on the vacuum insulation pipeline. The air and other gases in the double-layer structure can be discharged through the vacuum pumping device. After vacuuming, the interface C4 is sealed with a plug to form a highly vacuum environment, thereby greatly reducing the heat conduction and convection of gas molecules and improving the insulation effect.

[0042] The tank wall of the liquid nitrogen cryogenic tank 1 is also a double-layer structure, and the outer two layers are an insulating layer. In this embodiment, the inner and outer walls of the liquid nitrogen cryogenic tank 1 are filled with high thermal insulation polymer foam material and aluminum silicate insulation cotton to form an intermediate "insulating layer". In other embodiments, the inner and outer layers of the tank wall of the liquid nitrogen cryogenic tank 1 may be in a vacuum state to form a vacuum insulation layer.

[0043] The inner and outer layers of the tank wall of the liquid nitrogen cryogenic tank 1 are insulated, which can effectively reduce the external heat from entering the liquid helium cooling chamber 2 through conduction, and help maintain the low temperature state of the liquid helium cooling chamber 2, thereby reducing the vaporization loss of liquid helium, reducing the amount of liquid helium, reducing the test cost, improving the cooling efficiency and maintaining the stability of the low temperature environment. The double cold preservation structure can reduce the overall heat leakage of the valve 100 to be tested, improve the utilization rate of liquid helium, and reduce the consumption of liquid helium.

[0044] The liquid helium cooling chamber 2 is made of wound flame-retardant low-temperature insulation aluminum foil composite material and is made using a multi-layer insulation coating process. This vacuum insulation layer is integrated with the liquid helium inlet vacuum insulation pipeline. The entire outer layer is also a fully sealed structure. After the helium test is qualified, it is vacuumed at the interface C4. The vacuum degree of the entire outer layer at the liquid nitrogen temperature should not be greater than 5×10 -3 Pa.

[0045] The liquid helium cooling chamber 2 is arranged in the liquid nitrogen low temperature tank 1. On the one hand, it provides a dual cold preservation effect for the valve 100 to be tested, and on the other hand, it further realizes a more efficient use of liquid helium, further reduces the consumption of liquid helium, and reduces the test cost. The specific principle is as follows: the test structure is subjected to heat transfer analysis, the innermost volume cavity is the liquid helium cooling source, and the liquid helium evaporation rate is determined by the volume temperature of the liquid helium cooling chamber 2, that is, the two surface temperatures of the volume cavity are formed, namely, the outer surface temperature of the valve body and the inner wall temperature of the liquid helium cooling chamber 2. In order to reduce the thermal influence of the inner wall temperature of the liquid helium cooling chamber 2 on the liquid helium, the liquid helium cooling chamber 2 is placed in a low temperature liquid nitrogen tank at -196°C for cooling and cold preservation during the test. In order to further reduce the consumption of liquid helium, it is necessary to control the outer surface temperature of the valve body. The outer surface temperature of the valve body is, from top to bottom, a temperature gradient formed by heat conduction between the ambient temperature and the liquid helium temperature, and the temperature at each location can be measured by the temperature sensor described below.

[0046] Reference Figure 3 The air inlet branch 5 is used to communicate with the air inlet 101 of the valve 100 to be tested, and introduce helium into the valve 100 to be tested; the air outlet branch 6 is used to communicate with the air outlet 102 of the valve 100 to be tested, and is used to determine the sealing condition of the valve 100 to be tested.

[0047] The intake branch 5 comprises a first helium storage device 52 and a first booster pump 53 which are connected in sequence through an intake pipe 51, and one end of the intake branch 5 away from the first helium storage device 52 is connected to the switching device. A helium pressure regulating valve V1 is provided on the intake pipe 51 near the first helium storage device 52, and an upstream isolation valve V2 is provided on the intake pipe 51 near the liquid helium cooling chamber 2. The first helium storage device 52 is a first helium cylinder, and a pressure sensor is provided on the first helium cylinder to measure the outlet pressure of the first helium cylinder.

[0048] Two pressure sensors are provided on the air intake pipe 51, which are located on both sides of the first booster pump 53, respectively, and are used to measure the pressure in the air intake pipe 51. The first pressure sensor is located before the first booster pump 53, and is used to detect the pressure of the original gas, while the second pressure sensor is located after the first booster pump 53, and is used to monitor the pressure after boosting. The pressure change of the gas before and after boosting can be monitored in real time, which is conducive to ensuring the stability of the gas pressure and predicting potential pressure problems. The pressure difference before and after boosting is compared, so as to adjust the working state of the first booster pump 53 and ensure that the gas pressure meets the test requirements.

[0049] The air outlet branch 6 includes an air outlet pipe 61, an alcohol bubble counter 62 and an exhaust pipe 63. One end of the air outlet pipe 61 extends into the bottom of the alcohol bubble counter 62, and the other end is connected to the switching device. A downstream isolation valve V4 is provided on the air outlet pipe 61 near the alcohol bubble counter 62, and a pressure sensor may be provided on the air outlet pipe 61. One end of the exhaust pipe 63 extends into the top of the alcohol bubble counter 62, and the other end is used for exhaust. The sealing degree of the valve 100 to be tested can be judged by the number of bubbles in the alcohol bubble counter 62. A flow meter 64 is provided on the exhaust pipe 63 to measure the flow of the air outlet pipe 61, so as to more accurately judge the sealing property of the valve 100 to be tested. The flow meter 64 can be used to measure the instantaneous leakage, the cumulative leakage and the average leakage.

[0050] Continue to refer to Figure 3 One end of the first gas guide pipe 13 passes through the liquid helium cooling chamber 2 to communicate with the first interface 101 of the valve to be tested 100; one end of the second gas guide pipe 14 passes through the liquid helium cooling chamber 2 to communicate with the second interface 102 of the valve to be tested 100; the other end of the first gas guide pipe 13 and the other end of the second gas guide pipe 14 are connected to the inlet branch 5 and the outlet branch 6 through a switching device, and the switching device has a forward state and a reverse state.

[0051] When the switching device is in the forward state, the first air duct 13 is connected to the air outlet branch 6, and the second air duct 14 is connected to the air inlet branch 5; when the switching device is in the reverse state, the first air duct 13 is connected to the air inlet branch 5, and the second air duct 14 is connected to the air outlet branch 6.

[0052] Reference Figure 1 The switching device includes a first switching pipe 15 and a second switching pipe 16 .

[0053] One end of the first switching pipe 15 is connected to the intake branch 5, and the other end is connected to the outlet branch 6. The first switching pipe 15 is provided with a stop valve V16 and a stop valve V18. The first air guide pipe 13 is connected to the middle part of the first switching pipe 15 and is located between the stop valve V16 and the stop valve V18.

[0054] One end of the second switching pipe 16 is connected to the intake branch 5, and the other end is connected to the outlet branch 6. The second switching pipe 16 is provided with a stop valve V17 and a stop valve V19. The second air guide pipe 14 is connected to the middle part of the second switching pipe 16 and is located between the stop valve V17 and the stop valve V19.

[0055] 3, the stop valve V16 and the stop valve V19 are opened, and the stop valve V17 and the stop valve V18 are closed, so that the air inlet branch 5 is connected with the first air guide pipe 13, and the air outlet branch 6 is connected with the second air guide pipe 14. The helium in the first helium storage device 52 flows into the air inlet 101 of the valve to be tested 100 through the stop valve V16 and the first air guide pipe 13, flows out of the air outlet 102 of the valve to be tested 100, and flows into the air outlet branch 6 through the second air guide pipe 14 and the stop valve V19, so as to realize the positive sealing test of the valve to be tested 100.

[0056] Reference Figure 4 , open the stop valve V17 and the stop valve V18, close the stop valve V16 and the stop valve V19, so that the air inlet branch 5 is connected with the second air guide pipe 14, and the air outlet branch 6 is connected with the first air guide pipe 13, and the helium in the first helium storage device 52 flows into the air outlet 102 of the valve 100 to be tested through the stop valve V17 and the second air guide pipe 14, flows out of the air inlet 101 of the valve 100 to be tested, and flows into the air outlet branch 6 through the first air guide pipe 13 and the stop valve V18, so as to realize the reverse sealing test of the valve 100 to be tested.

[0057] At least part of the first gas conduit 13 and the second gas conduit 14 is a serpentine tube. In this embodiment, part of the first gas conduit 13 located in the liquid nitrogen cryogenic tank 1 is a serpentine tube, which increases the length of the conduit. Since the helium in the first helium storage device 52 is at room temperature and the valve 100 to be tested is at low temperature, the helium flows in the first gas conduit 13. The first gas conduit 13 is a serpentine tube, which can extend the time for the helium to flow in the first gas conduit 13, promote the heat exchange between the helium and the liquid nitrogen in the liquid nitrogen cryogenic tank 1, and the liquid nitrogen in the liquid nitrogen cryogenic tank 1 can pre-cool the room temperature helium to prevent the room temperature helium from directly entering the valve 100 to be tested and causing the temperature of the valve 100 to rise.

[0058] Part of the second gas conduit 14 in the liquid nitrogen cryogenic tank 1 is a serpentine tube, which increases the length of the conduit. The cryogenic helium flows out from the valve 100 to be tested. The second gas conduit 14 is a serpentine tube, which can extend the flow time of the cryogenic helium in the second gas conduit 14, promote heat exchange between the cryogenic helium and the liquid nitrogen in the liquid nitrogen cryogenic tank 1, and the liquid nitrogen in the liquid nitrogen cryogenic tank 1 can rewarm the cryogenic helium.

[0059] Reference Figure 1 The temperature measurement component includes a first temperature sensor TC1, a second temperature sensor TC2, a third temperature sensor TC3, a fourth temperature sensor TC4, a fifth temperature sensor TC5, and a sixth temperature sensor TC6.

[0060] The first temperature sensor TC1 is arranged in the liquid helium cooling chamber 2, and is used to measure the temperature of the liquid helium in the liquid helium cooling chamber 2; the second temperature sensor TC2 is arranged on the valve to be tested 100, and is used to measure the temperature of the valve to be tested 100; the third temperature sensor TC3 is arranged at the bottom of the outer wall of the valve pipe, and is used to measure the temperature of the bottom of the valve pipe; the fourth temperature sensor TC4 is arranged at the top of the outer wall of the valve pipe, and is used to measure the temperature of the top of the valve pipe; the fifth temperature sensor TC5 is arranged at the valve cover stuffing box of the valve to be tested 100, and is used to measure the stuffing temperature; the sixth temperature sensor TC6 is arranged in the external environment, and is used to measure the temperature of the external environment.

[0061] Combination Figure 1 and Figure 5 The liquid hydrogen temperature zone valve bidirectional sealing test system also includes a heating branch 17, which includes a heater 171 and a second booster pump 172 connected in sequence through pipelines. One end of the heating branch 17 can be selectively connected to the first helium storage device 52, and the other end can be selectively connected to the first gas guide pipe 13. Specifically, a 2-position 3-way solenoid valve V15 is provided on the intake branch 5, and the heating branch 17 is connected to the 2-position 3-way solenoid valve V15. The end of the heating branch 17 away from the intake branch 5 is connected to the first switching pipe 15 to achieve communication with the first gas guide pipe 13.

[0062] The temperature measuring assembly also includes a seventh temperature sensor TC7 and an eighth temperature sensor TC8 disposed on the heating branch 17. The seventh temperature sensor TC7 and the eighth temperature sensor TC8 are located on both sides of the heater 171. The seventh temperature sensor TC7 is used to measure the temperature of the helium before entering the heater 171, and the eighth temperature sensor TC8 is used to measure the temperature of the helium discharged from the heater 171. The first booster pump 53 and the second booster pump 172 are pneumatic booster pumps, and the driving sources include but are not limited to compressed air, nitrogen, etc. The heater 171 is a coil heater, including but not limited to an electric heater, a steam heater, etc.

[0063] Reference Figure 5 The helium pressurization recovery process is as follows: before the switching device is switched, the valve to be tested 100 is in an open state, the upstream isolation valve V2 is opened, the downstream isolation valve V4 is closed, the pressure relief valve V20 is kept closed, the stop valve V17 and the stop valve V18 are opened, and the stop valve V16 and the stop valve V19 are closed, or the stop valve V17 and the stop valve V18 are closed, the stop valve V16 and the stop valve V19 are opened, and the interlock control 2-position 3-way solenoid valve V15 is switched, so that the second boosting pump 172 is disconnected from the first helium device and connected to the first boosting pump 53, so that the heating branch 17, the second boosting pump 172, the first boosting pump 53, the first gas guide pipe 13, the valve to be tested 100 and the second gas guide pipe 14 form a loop, and the second boosting pump 172 and the heater 171 are started to heat the helium in the loop.

[0064] Reference Figure 6 The timing of starting the coil heater 171 is determined according to the temperature measured by the seventh temperature sensor TC7, so that the low-temperature helium in the valve 100 to be tested can be reheated. After the temperature measured by the eighth temperature sensor TC8 reaches normal temperature, the interlock control 2-position 3-way solenoid valve V15 is switched, so that the second booster pump 172 is connected to the first helium device, the first booster pump 53 is disconnected from the first helium device, and the second booster pump 172 is started synchronously to recover the helium in the valve 100 to be tested. According to the pressures measured by the first pressure sensor and the second pressure sensor, it is determined whether the recovery is completed (if the pressure measured by the first pressure sensor is close to the maximum allowable pressure of the helium cylinder, the boosting is stopped, or if the first pressure sensor does not reach the maximum allowable pressure of the helium cylinder, but the pressure of the second pressure sensor is at normal pressure, the boosting is stopped), and the second booster pump 172 and the heater 171 stop working. Control the 2-position 3-way solenoid valve V15 to switch the pipeline. According to the above rules, operate the stop valve V16 to stop valve V19 to switch the pipeline inlet and outlet. After the switching is completed, open the upstream isolation valve V2 to perform forward and reverse valve sealing tests.

[0065] Reference Figure 1 The heating pipeline is connected to a discharge pipeline, and the discharge pipeline is connected to a pressure relief valve V20 to avoid excessive pressure in the pipeline.

[0066] The second gas guide pipe 14 is connected to the first discharge pipe 8, and a purge valve V3 is provided on the first discharge pipe 8. The first discharge pipe 8 is provided to prevent excessive pressure or potential explosion risks caused by gas accumulation, and to remove residual gas in the pipe, thereby ensuring the cleanliness of the inside of the pipe and avoiding gas leakage or cross contamination.

[0067] The top of the liquid helium cooling chamber 2 is connected to the second discharge pipe 9, and the second discharge pipe 9 is connected to the discharge valve V5 and / or the safety valve V6. In this embodiment, the second discharge pipe 9 is connected to the safety valve V6 and the discharge valve V5 in sequence in the direction away from the liquid helium cooling chamber 2.

[0068] When the pressure in the liquid helium cooling chamber 2 is too high, the excess pressure can be released through the safety valve V6 to prevent equipment damage or safety accidents caused by pressure accumulation. The interior of the liquid helium cooling chamber 2 is a completely sealed chamber. Since the latent heat of vaporization of liquid helium is low, it is very easy to vaporize. In order to ensure the safety of the test, the discharge valve V5 can be used for the normal discharge of liquid helium after vaporization during the cooling process, and the safety valve V6 is used as a protection device to automatically discharge gas when the system pressure exceeds the predetermined safety value to ensure the safe operation of the system, improve the reliability of the system, ensure that the pressure can be released in time in extreme cases, avoid potential safety risks, and facilitate daily system maintenance and pressure control.

[0069] Reference Figure 7 The heat conducting coil 10 is located in the liquid helium cooling chamber 2 and is used to be wound around the valve pipe. One end passes through the liquid helium cooling chamber 2 and is selectively connected to the liquid guide tube 110, and the other end passes through the liquid helium cooling chamber 2 and is connected to the liquid nitrogen cryogenic tank 1. Specifically, a liquid nitrogen inlet valve V10 is provided at one end of the heat conducting coil 10 close to the liquid guide tube 110, and a liquid nitrogen drain valve V11 is provided at one end of the heat conducting coil 10 close to the liquid nitrogen cryogenic tank 1. The liquid nitrogen in the liquid nitrogen storage device 3 flows through the liquid nitrogen inlet valve V9 and the liquid nitrogen inlet valve V10 and is introduced into the heat conducting coil 10, so that it is fully heat-exchanged with the outer surface of the valve pipe and then discharged into the liquid nitrogen cryogenic tank 1 through the liquid nitrogen drain valve V11, and the valve pipe is cooled by the low temperature characteristics of the liquid nitrogen.

[0070] By directly introducing liquid nitrogen into the contact point of the valve pipe, the heat conduction effect is enhanced, thereby more effectively reducing the temperature of the valve 100 to be tested to meet the strict requirements of the liquid hydrogen temperature range valve test. To ensure the heat exchange effect, the heat conducting coil 10 can be made of metal with good thermal conductivity, including but not limited to silver, copper, gold, aluminum and other materials.

[0071] Furthermore, the system further includes a first connecting pipe 11 and a second connecting pipe 12. One end of the first connecting pipe 11 is connected to one end of the second gas guiding pipe 14 close to the liquid helium cooling chamber 2, and the other end is connected to the liquid guiding pipe 110, and a stop valve V12 is provided on the first connecting pipe 11. One end of the second connecting pipe 12 is connected to one end of the first gas guiding pipe 13 close to the liquid helium cooling chamber 2, and the other end is connected to the liquid nitrogen cryogenic tank 1, and a stop valve V13 is provided on the second connecting pipe 12.

[0072] Close other valves, open only the valve 100 to be tested, and then open the liquid nitrogen inlet valve V9, and add liquid nitrogen into the liquid nitrogen cryogenic tank 1 to soak the entire valve 100 to be tested. Then open the stop valve V13, slowly open the stop valve V12, and the liquid nitrogen in the liquid nitrogen storage device 3 flows into the valve 100 to be tested, and then flows into the liquid nitrogen cryogenic tank 1. The liquid nitrogen directly flows into the valve 100 to be tested to cool the valve 100 to be tested, and quickly reduces the temperature of the valve 100 to be tested to -180°C, thereby improving the cooling efficiency and shortening the cooling time of the valve 100 to be tested before the test.

[0073] The temperature of each part is monitored by the temperature sensor. The liquid nitrogen inlet valve V10 and the liquid nitrogen discharge valve V11 are opened according to the temperature change to introduce liquid nitrogen into the heat transfer coil 10. When the temperature of the valve 100 to be tested reaches -180°C, the stop valve V12 and the stop valve V13 are closed.

[0074] Open the purge valve V3, adjust the helium pressure regulating valve V1 to adjust the cylinder outlet pressure to 1MPa, open the upstream isolation valve V2, and introduce helium into the entire test pipeline to purge the liquid nitrogen accumulated in the pipe. The helium is discharged from the C2 port. After the purge is completed, close the purge valve V3.

[0075] Open the liquid helium regulating valve V7 and the helium regulating valve V8, introduce liquid helium into the liquid helium cooling chamber 2, and use the temperature sensor to monitor the temperature of each part of the valve 100 to be tested. When the temperature of the valve 100 to be tested reaches -253°C and stabilizes, switch the valve 100 to be tested to a closed state.

[0076] Open the downstream isolation valve V4, adjust the helium pressure regulating valve V1 to introduce helium of the required pressure value into the test pipeline according to the test requirements, and test the performance of the liquid hydrogen valve at -253℃.

[0077] For liquid hydrogen check valves, if the internal cooling method is used, the cooling medium needs to be passed in the forward direction to cool to -253°C. During the test, helium needs to be passed in the reverse direction for pressure testing. In addition, for some valves with a two-way sealing structure, when conducting a sealing test, it is necessary to switch the forward and reverse directions to pass helium for a pressurization test. If this is achieved by replacing the inlet and outlet pipes of the experimental module, the test efficiency will be greatly reduced. At the same time, when switching the pipes, air will be brought into the pressure test pipe. At the low temperature of -253°C, the air will condense and block the test pipeline.

[0078] The control device is electrically connected or communicated with each valve, each temperature sensor, each pressure sensor, flow meter 64, alcohol bubble meter 62, etc., to control the adjustment action and switch switching of the pneumatic valve, so as to realize automatic control, and at the same time obtain the temperature, pressure, flow and other measurement parameters of each key part during the monitoring test. The measurement parameters include the ambient temperature, the liquid helium temperature in the liquid helium cooling chamber 2, the temperature of the valve 100 to be tested, the packing temperature, the outlet pressure of the first helium cylinder, the outlet pressure of the second helium cylinder, the pressure before the valve, the pressure after the valve, the outlet pressure of the liquid helium tank 42, the instantaneous leakage, the cumulative leakage, the average leakage, etc.

[0079] The embodiment of the present application also provides a liquid hydrogen temperature zone valve bidirectional sealing test method, using the liquid hydrogen temperature zone valve bidirectional sealing test system, comprising the following steps: The valve to be tested 100 is installed in the liquid helium cooling chamber 2 , the air inlet 101 of the valve to be tested 100 is connected to the air inlet pipe 51 , and the air outlet 102 of the valve to be tested 100 is connected to the air outlet pipe 61 .

[0080] Open the liquid nitrogen inlet valve V9, and introduce liquid nitrogen into the liquid nitrogen cryogenic tank 1. At this time, the liquid helium cooling chamber 2 is in a double-layer structure and is always in a vacuum state. Open the stop valve V12 and the stop valve V13, and introduce liquid nitrogen into the valve to be tested 100. Open the liquid nitrogen inlet valve V10 and the liquid nitrogen drain valve V11, and introduce the liquid nitrogen into the heat transfer coil 10 to cool the valve to be tested 100. First, use liquid nitrogen, which has a wider source and a cheaper price, as a cooling medium to cool the valve to be tested 100 to -150°C, or even lower, and the lowest can be cooled to -196°C. This temperature is related to the cooling time.

[0081] When the second temperature sensor TC2 detects that the temperature of the valve 100 to be tested reaches the first preset temperature, which can be set between -150°C and -196°C, the stop valve V12 and the stop valve V13 are closed. Liquid helium is introduced into the liquid helium cooling chamber 2, and liquid helium is used as a cooling medium to continue cooling, so that the valve 100 to be tested is further cooled; when the second temperature sensor TC2 detects that the temperature of the valve 100 to be tested reaches the second preset temperature, the second preset temperature is less than the first preset temperature, and the second preset temperature is set to -253°C. The test main circuit is turned on, the valve 100 to be tested is closed, helium is introduced into the valve 100 to be tested through the air inlet branch 5, and the sealing condition of the valve 100 to be tested is determined through the air outlet branch 6.

[0082] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0083] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A liquid hydrogen temperature zone valve bidirectional sealing test system, characterized in that: include: A cryogenic container comprising a liquid nitrogen cryogenic tank (1) and a liquid helium cooling chamber (2); The liquid nitrogen cryogenic tank (1) is selectively connected to the liquid nitrogen storage device (3) via a liquid guide tube (110); the liquid helium cooling chamber (2) comprises a closed chamber, which is located in the liquid nitrogen cryogenic tank (1) and selectively connected to the liquid helium storage device (4) via a liquid inlet tube (210), and is used to accommodate a valve body of a valve to be tested (100); the valve to be tested (100) is provided with a first interface (101) and a second interface (102); An air inlet branch (5) is used to communicate with a first interface (101) of the valve to be tested (100) and introduce helium into the valve to be tested (100); An air outlet branch (6) is used to communicate with a second interface (102) of the valve to be tested (100) and is used to determine the sealing condition of the valve to be tested (100); A first gas guide pipe (13), one end of which passes through the liquid helium cooling chamber (2) and is used to communicate with a first interface (101) of the valve to be tested (100); A second air guide pipe (14), one end of which passes through the liquid helium cooling chamber (2) and is connected to a second interface (102) of the valve to be tested (100); the other end of the first air guide pipe (13) and the other end of the second air guide pipe (14) are connected to an air inlet branch (5) and an air outlet branch (6) via a switching device, wherein the switching device has a forward state and a reverse state; When the switching device is in a forward state, the first air duct (13) is connected to the air outlet branch (6), and the second air duct (14) is connected to the air inlet branch (5); when the switching device is in a reverse state, the first air duct (13) is connected to the air inlet branch (5), and the second air duct (14) is connected to the air outlet branch (6).

2. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 is characterized in that: The switching device comprises: A first switching pipeline (15), one end of which is in communication with the air inlet branch (5) and the other end of which is in communication with the air outlet branch (6); two stop valves are provided on the first switching pipeline (15); the first air guide pipeline (13) is in communication with the middle of the first switching pipeline (15) and is located between the two stop valves; The second switching pipeline (16) has one end connected to the air inlet branch (5) and the other end connected to the air outlet branch (6). The second switching pipeline (16) is provided with two stop valves. The second air guide pipeline (14) is connected to the middle part of the second switching pipeline (16) and is located between the two stop valves.

3. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 is characterized in that: The device also comprises a heating branch (17), wherein the heating branch (17) comprises a heater (171) and a second booster pump (172) which are connected in sequence through pipelines; one end of the heating branch (17) can be selectively connected to the first helium storage device (52), and the other end is connected to the first gas guide pipeline (13).

4. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 3 is characterized in that: Two pressure sensors are provided on the air intake branch (5), one of the pressure sensors being located between the first helium storage device (52) and the heating branch (17), and the other pressure sensor being used to measure the pressure of the second air guide pipe (14).

5. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 is characterized in that: It also includes a heat-conducting coil (10), and a valve connecting pipe is provided on the valve to be tested (100); The heat conducting coil (10) is located in the liquid helium cooling chamber (2) and is used to be wound around the valve pipe. One end of the heat conducting coil passes through the liquid helium cooling chamber (2) and is selectively connected to the liquid conducting pipe (110), and the other end passes through the liquid helium cooling chamber (2) and is connected to the liquid nitrogen cryogenic tank (1).

6. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 or 5, characterized in that: Also includes: a first connecting pipe (11), one end of which is in communication with the second air guide pipe (14) and the other end of which is in communication with the liquid guide pipe (110), and a stop valve is provided on the first connecting pipe (11); A second connecting pipe (12) is connected at one end to the first gas guide pipe (13) and at the other end to the liquid nitrogen cryogenic tank (1); a stop valve is provided on the second connecting pipe (12).

7. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 is characterized in that: The wall of the liquid helium cooling chamber (2) is a double-layer structure and is provided with an interface for communicating with a vacuum pumping device.

8. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 is characterized in that: The tank wall of the liquid nitrogen low-temperature tank (1) is a double-layer structure, and an insulating layer is provided between the inner and outer layers.

9. The liquid hydrogen temperature zone valve bidirectional sealing test system according to claim 1 is characterized in that: It also comprises a temperature measuring component, wherein the temperature measuring component comprises a second temperature sensor (TC2), and the second temperature sensor (TC2) is used to be arranged on the valve to be tested (100) to measure the temperature of the valve to be tested (100).

10. A bidirectional sealing test method for valves in liquid hydrogen temperature zone, characterized in that: Based on the liquid hydrogen temperature zone valve bidirectional sealing test system as described in any one of claims 1 to 9, the following steps are included: The valve to be tested (100) is installed in the liquid helium cooling chamber (2) and is connected to the air inlet branch (5) and the air outlet branch (6); Introducing liquid nitrogen into the liquid nitrogen cryogenic tank (1) to cool the valve to be tested (100); Introducing liquid helium into the liquid helium cooling chamber (2) to further cool the valve to be tested (100); After the temperature is lowered, the first air guide pipe (13) is connected to the air outlet branch (6), the second air guide pipe (14) is connected to the air inlet branch (5), the valve to be tested (100) is closed, helium is introduced into the valve to be tested (100) through the air inlet branch (5), and the positive sealing condition of the valve to be tested (100) is determined through the air outlet branch (6); The first air guide pipe (13) is connected to the air inlet branch (5), the second air guide pipe (14) is connected to the air outlet branch (6), the valve to be tested (100) is closed, helium is introduced into the valve to be tested (100) through the air inlet branch (5), and the reverse sealing condition of the valve to be tested (100) is determined through the air outlet branch (6).

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